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 * Copyright (c) 2003, 2013, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
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 */

package javax.xml.xpath;

import java.io.PrintWriter;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.ObjectStreamField;
import java.io.InvalidClassException;

/**
 * <code>XPathException</code> represents a generic XPath exception.</p>
 *
 * @author <a href="Norman.Walsh@Sun.com">Norman Walsh</a>
 * @author <a href="mailto:Jeff.Suttor@Sun.COM">Jeff Suttor</a>
 * @since 1.5
 */
public class XPathException extends Exception {

  private static final ObjectStreamField[] serialPersistentFields = {
      new ObjectStreamField("cause", Throwable.class)
  };

  /**
   * <p>Stream Unique Identifier.</p>
   */
  private static final long serialVersionUID = -1837080260374986980L;

  /**
   * <p>Constructs a new <code>XPathException</code>
   * with the specified detail <code>message</code>.</p>
   *
   * <p>The <code>cause</code> is not initialized.</p>
   *
   * <p>If <code>message</code> is <code>null</code>,
   * then a <code>NullPointerException</code> is thrown.</p>
   *
   * @param message The detail message.
   * @throws NullPointerException When <code>message</code> is <code>null</code>.
   */
  public XPathException(String message) {
    super(message);
    if (message == null) {
      throw new NullPointerException("message can't be null");
    }
  }

  /**
   * <p>Constructs a new <code>XPathException</code>
   * with the specified <code>cause</code>.</p>
   *
   * <p>If <code>cause</code> is <code>null</code>,
   * then a <code>NullPointerException</code> is thrown.</p>
   *
   * @param cause The cause.
   * @throws NullPointerException if <code>cause</code> is <code>null</code>.
   */
  public XPathException(Throwable cause) {
    super(cause);
    if (cause == null) {
      throw new NullPointerException("cause can't be null");
    }
  }

  /**
   * <p>Get the cause of this XPathException.</p>
   *
   * @return Cause of this XPathException.
   */
  public Throwable getCause() {
    return super.getCause();
  }

  /**
   * Writes "cause" field to the stream.
   * The cause is got from the parent class.
   *
   * @param out stream used for serialization.
   * @throws IOException thrown by <code>ObjectOutputStream</code>
   */
  private void writeObject(ObjectOutputStream out)
      throws IOException {
    ObjectOutputStream.PutField fields = out.putFields();
    fields.put("cause", (Throwable) super.getCause());
    out.writeFields();
  }

  /**
   * Reads the "cause" field from the stream.
   * And initializes the "cause" if it wasn't
   * done before.
   *
   * @param in stream used for deserialization
   * @throws IOException thrown by <code>ObjectInputStream</code>
   * @throws ClassNotFoundException thrown by <code>ObjectInputStream</code>
   */
  private void readObject(ObjectInputStream in)
      throws IOException, ClassNotFoundException {
    ObjectInputStream.GetField fields = in.readFields();
    Throwable scause = (Throwable) fields.get("cause", null);

    if (super.getCause() == null && scause != null) {
      try {
        super.initCause(scause);
      } catch (IllegalStateException e) {
        throw new InvalidClassException("Inconsistent state: two causes");
      }
    }
  }

  /**
   * <p>Print stack trace to specified <code>PrintStream</code>.</p>
   *
   * @param s Print stack trace to this <code>PrintStream</code>.
   */
  public void printStackTrace(java.io.PrintStream s) {
    if (getCause() != null) {
      getCause().printStackTrace(s);
      s.println("--------------- linked to ------------------");
    }

    super.printStackTrace(s);
  }

  /**
   * <p>Print stack trace to <code>System.err</code>.</p>
   */
  public void printStackTrace() {
    printStackTrace(System.err);
  }

  /**
   * <p>Print stack trace to specified <code>PrintWriter</code>.</p>
   *
   * @param s Print stack trace to this <code>PrintWriter</code>.
   */
  public void printStackTrace(PrintWriter s) {

    if (getCause() != null) {
      getCause().printStackTrace(s);
      s.println("--------------- linked to ------------------");
    }

    super.printStackTrace(s);
  }
}
